Show Full P4V Log

I don't think there is a way.

The next best thing is switching on the output logging, using P4V's Edit | Preferences | Logging | Show p4 command output for file operations. With that, a command like yours would produce a log along the lines of

p4 revert -a somefile somefile {9 more items}
//depot/somefile#12 - was edit, reverted
//depot/mercury#1 - was edit, reverted
//depot/venus#2 - was edit, reverted
//depot/earth#3 - was edit, reverted
//depot/mars#4 - was edit, reverted
//depot/jupiter#5 - was edit, reverted
//depot/saturn#6 - was edit, reverted
//depot/uranus#7 - was edit, reverted
//depot/neptune#8 - was edit, reverted
//depot/pluto#9 - was delete, reverted

I've also tried switching on logging into file but that gives the same output (plus timestamps).